Beamforming is a signal preprocessing technology based on an antenna array. In beamforming, a directional beam is generated by adjusting a weighting coefficient of each array element in the antenna array, to obtain a significant array gain. In a cellular communications system, an antenna array including a plurality of antennas is usually deployed on a base station side, and a beamforming technology is used in downlink, thereby improving communication quality of the downlink. Such a directional beam is usually referred to as a narrow beam. Comparatively, if a base station uses a relatively small quantity of transmit antennas and does not use the beamforming technology, downlink transmission patterns of the base station are collectively referred to as wide beams.
In the prior art, the base station completes an energy estimation of a narrow beam by using an uplink pilot signal. Due to a difference between an uplink channel and a downlink channel, channel energy estimation of the narrow beam may be inaccurate, affecting transmission efficiency.